Nervous system study guide Flashcards
Label and describe the functions of
- dendrites
- cell body
- axon
- myelin
- Schwann cells
- Nodes of Ranvier
- synaptic endings
- motor end plates
- dendrites: takes impulses to cell body
- cell body: controls all metabolic functions (makes neurotransmitters)
- axon: takes impulses away from cell body
- myelin: lipid, insulates axon
- Schwann cells: produces myelin (lipid)
- Nodes of Ranvier: gaps between schwann cells
- synaptic endings: holds neurotransmitters via vesicles
- postsynaptic membrane: the membrane of the next neuron that contains receptors.
what happens during
- resting potential
- depolarization
- repolarization
- refractory period
resting potential:
- the neuron is not fired. Na is outside axon and K and large negative organic ion are inside the axon. Membrane potential is at -65mV. Neuron is ready to fire.
depolarization:
- Na+ gates open allowing Na ions in the axon and making the neuron positive (diffusion)(40 mV)
repolarization:
- K+ ions open allowing K ions to move out of the axon (diffusion)(-65 mV)
refractory period:
- Na+/K+ pump moves Na ions out of the axon and K ions back inside the axon ( ATP using a carrier protein) (-60 mV)
where does Interneuron communication occur
Interneuron communication occurs in the CNS only
Similarities and differences in structure of
- sensory neuron
- interneuron
- motor neuron
sensory neuron:
- long dendrites
- short axon
interneuron:
- long or short dendrites
- long or short axon
motor neuron
- short dendrites
- long axon
define:
- saltatory transmissions
- integration
- graph of voltage changes during action potential (describe what is occurring at each point of the graph and why does the potential difference change as a result)
saltatory transmissions: electrical impulse that jumps from node to node down the full length of an axon.
integration: the ratio of excitatory and inhibitory NT’s
Graph of voltage changes during action potential:
Resting potential:
- when a nerve is not conducting an impulse (-60 mV)
Depolarization: Na+ gates open allowing Na ions in the axon and making the neuron positive (diffusion)(40 mV)
Repolarization:
- K+ ions open allowing K ions to move out of the axon (diffusion)(-65 mV)
Recovery period:
- Na+/K+ pump moves Na ions out of the axon and K ions back inside the axon ( ATP using a carrier protein) (-60 mV)
-
what is the advantage of having a myelinated neuron?
Speeds up the speed of transmission (200m/s)
Describe how neurotransmitters are used in
the communication between neurons
The neurotransmitter travels across the synapse to excite or inhibit the target neuron by attaching to their specified receptor(s)
explain the steps involved for neurotransmitters ( beginning with the fusion of neurotransmitter with pre-synaptic membrane to the lock and key)
- Ca ions move into synaptic ending (diffusion)
- Ca ion cause contractile proteins to move synaptic vesicles to inner surface of presynaptic membrane
- Vesicle releases NT by exocytosis
- NT diffuse across synapse to postsynaptic membrane to bind of receptor protein sites using lock and key method
what ion is needed during interneuron communication and why?
Ca2+ because it allows the contractile fibers/proteins to move the synaptic vesicles to the inner surface of the presynaptic membrane.
what is meant by all-or-none?
an action potential is either triggered, or it isn’t
why are neurotransmitters packaged?
NT are package because if they are not packaged in vesicle, they will float around everywhere
why is synaptic transmission only one-way
Because only the ends of axons (synaptic endings) are able to release NT’s to affect the potential of the next neurons
examples of excitatory transmitters
Dopamine, Seratonin, Acetylcholine, Adrenalin, Noradrenalin
examples of inhibitory transmitters
GABA, glycine and serotonin
examples of neurological disorders due to neurotransmitter imbalances
Depression, Alzheimer’s , Parkinson’s, Schizophrenia
what are the 5 ways that drugs can affect synapse
- mimicry of NT,
- drugs attach to NTs, and prevents breakdown
- prevent NT to be released,
- Block receptor sites
- stimulate release of NT
what are the two main branches of the nervous system?
Somatic and Autonomic nervous system
similarities and differences between cranial nerves and spinal nerves
Similarities:
- Both are components of the PNS
Differences:
- Cranial nerves have 12 pairs
- Spinal nerves have 31 pairs
describe the sequences of events that occur during the knee-jerk reaction (reflex arc)
- stimulus (doctor hits patellar tendon) triggers action potential
- A nerve impulse is sent from sensory neuron to interneuron in spinal cord
- Instead of signal being sent to brain, it bypasses brain and nerve impulse is sent down motor neuron.
- Impulse goes to an effector organ (muscle or gland) that causes the knee to jerk causing you to remove the effector organ of the original stimulus
similarities and differences between Somatic nervous system and Autonomic nervous system
Similarities:
- none
Differences:
- somatic NS controls the body’s skeletal muscles
- Autonomic NS controls the glands and the muscles of the internal organs.
similarities and differences between Sympathetic vs. Parasympathetic system
Similarities:
-none
Differences:
- Sympathetic NS releases Noradrenalin
- Parasympathetic NS releases Acetylcholine
- Sympathetic NS is activated during emergency/ intense situations
- Parasympathetic NS is active during a state of normality
what neurotransmitters are used for the sympathetic and parasympathetic system
Noradrenalin and Acetylcholine
how does each system affect the organs
Parasympathetic: eyes: pupils constrict saliva gland: saliva production is increased heart: heart rate normal lungs: breathing rate normal stomach: digestion increases liver: excess glucose converted into glycogen bladder: sphincter relaxes
Sympathetic: eyes: pupils dilate saliva gland: saliva production reduced heart: heart rate increased lungs: breathing rate increased stomach: digestion inhibited liver: glycogen convert into glucose bladder: sphincter constricts
Functions of:
- medulla
- cerebellum
- midbrain
- hypothalamus
- thalamus
- ARAS
- cerebrum
- frontal lobe
- parietal lobe
- temporal lobe
- occipital lobe
medulla: controls heart and breathing rate, blood pressure, coughing, sneezing, vomiting hiccupping and swallowing
cerebellum: Precision, coordination and timing, posture
midbrain: central relay station
hypothalamus: regulates homeostasis by maintaining internal environment
thalamus: receives all sensory impulses (except smell) and sends them to appropriate regions of the cortexes for interpretation
ARAS: sorts out incoming stimuli, passing on to the cerebrum only those that require immediate attention.
cerebrum: voluntary movement, intelligence and memory
frontal lobe: movement, higher intellectual processes
parietal lobe: senses touch, temp, pressure, pain, understanding speech, using words
temporal lobe: hearing, smelling
occipital lobe: vision, combining visual experiences with other sensory experiences
